Potential changes in both the intensity and frequency of extreme drought events are vital aspects of regional climate change that can alter the distribution and dynamics of water availability and subsequently affect carbon cycles at the ecosystem level. The effects of extreme drought events on the carbon budget of peatland in the Zoige plateau and its response mechanisms were studied using an in-field controlled experimental method. The results indicated that the peatland ecosystem of the Zoige plateau functioned as a carbon sink while under the control (CK) or extreme drought (D) treatment throughout the entire growing season. Maximum fluxes of methane (CH₄) emissions and the weakest carbon sink activity from this ecosystem were in the early growth stage, the most powerful carbon sink activity was during the peak growth stage, while the absorption sink activity of carbon dioxide (CO₂) and CH₄ was present during the senescence stage. Extreme drought reduced the gross primary productivity (GPP) and ecosystem respiration (R_e) of the peatland ecosystem by 14.5% and 12.6%, respectively (p < 0.05) and the net ability to store carbon was reduced by 11.3%. Overall, the GPP was highly sensitive to extreme drought. Moreover, extreme drought significantly reduced the CH₄ fluxes of the ecosystem and even changed the peatland from a CH₄ emission source to a CH₄ sink. Subsequent to drought treatment, extreme drought was also shown to have a carry-over effect on the carbon budget of this ecosystem. Soil water content and soil temperature were the main driving factors of carbon budget change in the peatland of the Zoige plateau, but with the increase in soil depth, these driving forces were decreased. The findings indicated that frequent extreme drought events in the future might reduce the net carbon sink function of peatland areas, with an especially strong influence on CO₂.

Forest nitrous oxide (N₂O) emission plays an important role in the greenhouse gas budget of forest ecosystems. However, spatial variability in N₂O fluxes complicates the determination of key factors of N₂O fluxes at different scales. Based on an updated database of N₂O fluxes and the main edaphic factors of global forests, the magnitude of N₂O fluxes from forests and the relationships between edaphic factors and N₂O fluxes at different scales were analyzed. According to the results, the average annual N₂O flux of the global forest was 142.91 ± 14.1 mg N m⁻² year⁻¹. The range of total forest estimated N₂O emission was 4.45–4.69 Tg N in 2000. N₂O fluxes from forests with different leaf traits (broadleaved and coniferous) have significant differences in magnitude, whereas the leaf habit (evergreen and deciduous) was an important characteristic reflecting different patterns of N₂O seasonal variations. The main factors affecting N₂O fluxes on the global scale were ammonium (NH₄⁺) and nitrate (NO₃⁻) concentrations. With an increasing scale (from the site scale to the regional scale to the global scale), the explanatory power of the five edaphic factors to N₂O flux decreased gradually. In addition, the response curves of N₂O flux to edaphic factors were diversified among different scales. At both the global and regional scales, soil hydrothermal condition (water filled pore space (WFPS) and soil temperature) might not be the main spatial regulation for N₂O fluxes, whereas soil nutrient factors (particularly NO₃⁻ concentration) could contribute more on N₂O flux spatial variations. The results of site-control analysis demonstrated that there were high spatial heterogeneity of the main N₂O controls, showing N₂O fluxes from low latitude forests being more likely associated with soil WFPS and temperature. Thus, our findings provide valuable insights into the regulatory edaphic factors underlying the variability in N₂O emissions, when modeling at different scales.

The Zoige alpine peatlands are one of the highest and largest alpine peatlands in the world and play an important role in the global carbon cycle. Drainage is the main disturbance at Zoige, and the drawdown of the water table level changes CH₄ emissions. There is still much uncertainty relating to how CH₄ emissions respond to multiple water table levels. Here, we simulated six gradients (−30 cm, −20 cm, −10 cm, 0 cm, 10 cm, and 20 cm) of the water table level through a mesocosm manipulation experiment in the Zoige peatlands. The water table level had a significant effect on CH₄ emissions. CH₄ emissions did not change with water table levels from −30 cm to −10 cm, but significantly increased as the water table level increased above −10 cm. A significant log-linear relationship (R² = 0.44, p < 0.001) was found between CH₄ emissions and a water table level range from −10 to 20 cm. This study characterized the responses of CH₄ emissions to multiple water table levels and provide additional data for accurately evaluating CH₄ emissions. The results of this study also have several conservation implications for alpine peatlands.

Editorial: The impacts of climate change and human activities on the structure and function of wetland/grassland ecosystems

An in-depth understanding of the associations between variations in the wetland area and socio-economic driving forces is essential owing to rapid urbanization. However, to date, no study has performed a quantitative study on the relationships between spatio-temporal patterns for wetland area variations and socio-economic driving factors in Yunnan Province. Based on Statistical Yearbook data, we found that during 10 years, different types of wetlands exhibited different change rates, with obvious spatial heterogeneity. The overall increase in wetland area in Yunnan Province was 13.35%, of which the increases in river, lake, and swamp wetland areas were 46.39%, −3.12%, and 295.56%, respectively. At the city level, the maximum decrease and increase in total wetland area were noted in Xishuangbanna (−84.30%) and Diqing (+185.22%), respectively. A total of 9 of 24 factors which were further selected according to collinearity diagnostics might help interpret changes in the wetland area of Yunnan Province according to the regression analysis results (R² = 0.749, p < 0.01). Moreover, in different city development periods, the key socio-economic factors were different, which should be considered separately when formulating policies. Our results may clarify the socio-economic influencing factors for wetland spatio-temporal changes and help to guide policymakers.